Currently, the number of vehicles applied with a smart cruise control (SCC) system has been increasing.
The SCC system is a system that controls a vehicle to maintain an inter-vehicle distance by measuring an inter-vehicle distance with a preceding vehicle using radar.
Accordingly, in the SCC system, it is important to accurately measure the inter-vehicle distance with the preceding vehicle. However, detection capability of the radar varies based on an installation location of the radar. Specifically, generally used radar has performance of a vertical detection angle of about ±2 degrees to ±4 degrees in a vertical direction. When a detection angle is too large, a lower end of road or an upper structure of the road is erroneously detected. When the detection angle is too small, error recognition of a detection distance occurs based on the installation location of the radar.
In particular, when the radar is installed around a lower end of a license plate of a vehicle or around a fog lamp, and when ground clearance of the preceding vehicle is high or when a rear shape such as a ready-mixed concrete (RMC) truck is different from a general vehicle, the radar may not accurately verify an inter-vehicle distance.
Alternatively, even when the preceding vehicle is a heavy-duty truck and is a vehicle of which rear safety valve is illegally remodeled, the inter-vehicle distance may not be accurately measured.
When the inter-vehicle distance is not accurately measured, the SCC system may put the brake on the vehicle at a location closer to the preceding vehicle than expected. If the above occurs, a collision with the preceding vehicle may occur.
FIG. 1 is a diagram illustrating an example of a case in which an inter-vehicle distance is not accurately measured according to a related art.
Referring to FIG. 1, a preceding vehicle is a trailer having high ground clearance and existing inter-vehicle distance measurement is performed in such a manner that radar detects a wheel portion of the trailer, instead of detecting the rear of the vehicle. Accordingly, an error occurs in timing for an SCC system to put the brake on the vehicle and thus, a stoppage distance becomes faulty.
FIG. 2 is a graph illustrating an example of an inter-vehicle distance with the same preceding vehicle measured by an inter-vehicle distance measuring apparatus according to the related art.
Referring to FIG. 2, it can be known that the same circumstance as FIG. 1 occurred around 205 seconds and thus, an error of about 5 meters occurred within the inter-vehicle distance.
Accordingly, there is a need for a method of calculating an accurate inter-vehicle distance by correcting an error when the error occurs within an inter-vehicle distance with a preceding vehicle due to a variety of reasons.